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arXiv · 0712.1898

Multiphoton Transitions in a Spin System Driven by Strong Bichromatic Field

A. P. Saiko·G. G. Fedoruk·S. A. Markevich
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Abstract

EPR transient nutation spectroscopy is used to measure the effective field (Rabi frequency) for multiphoton transitions in a two-level spin system bichromatically driven by a transverse microwave (MW) field and a longitudinal radio-frequency (RF) field. The behavior of the effective field amplitude is examined in the case of a relatively strong MW field, when the derivation of the effective Hamiltonian cannot be reduced to first-order perturbation theory in w_{1} / w_{rf} (w_{1} is the microwave Rabi frequency, w_{rf} is the RF frequency). Experimental results are consistently interpreted by taking into account the contributions of second and third order in w_{1} / w_{rf} evaluated by Krylov-Bogolyubov-Mitropolsky averaging. In the case of inhomogeneously broadened EPR line, the third-order correction modifies the nutation frequency, while the second-order correction gives rise to a change in the nutation amplitude due to a Bloch-Siegert shift.

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A. P. Saiko, G. G. Fedoruk, S. A. Markevich. 2007-12-12. Multiphoton Transitions in a Spin System Driven by Strong Bichromatic Field. https://doi.org/10.1134/s1063776107110039

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